What do you mean by a car engine and transmission?

This blog post will answer the question, ‘What do you mean by a car engine and transmission?’, and cover topics like what does a car engine do, how does a car engine work, what is a car transmission and how does it work, and what are the main types of transmission used in cars.

What do you mean by a car engine and transmission?

A car engine is a setup made of different components that help convert forms of energy into mechanical energy, which is used to drive the car wheels through a crankshaft and transmission system.

A car transmission system is a component that transfers mechanical energy from the engine to the wheels to drive it and also helps in reducing the load on the engine, and reducing fuel consumption.

What does a car engine do?

A car engine or internal combustion(IC) engine converts chemical energy from the combustion of air and fuel inside the combustion chamber into mechanical energy. This energy is transferred to the crankshaft via the upward and downward movement of the pistons and finally to the wheels to help the car move.

These are some benefits of IC engines over external combustion engines:

  • High efficiency
  • Simpler design
  • Low weight-to-power ratio
  • Low initial cost
  • Less storage space required

How does a car engine work?

Typical car engines or an internal combustion engine usually works in a 4-stroke cycle. These are some of the main parts that participate in this cycle and the way they occur.

Cylinder head

This is the passage through which the fuel enters the cylinder and exhaust gases are discharged. Its main components are camshafts, spark plugs, and the different valves.

Cylinder block

This is the place where the combustion of the air-fuel mixture takes place. The main components of the cylinder block are pistons, the combustion chamber, and the crankshaft.

Oil sump

The oil sump makes up for the lower section of an engine block. Its main components are oil filters and an oil pan.

The 4 stroke cycle occurs in the following steps.

Intake stroke

The piston is dragged down by the movement of the crankshaft to let the inlet valve inject the air-fuel mixture into the combustion chamber.

Compression stroke

This stroke involves the inlet valve closing and the piston moving upwards to compress the air-fuel mixture, thus making it more flammable and allowing the spark plug to ignite it.

Power stroke

The energy and force generated due to the explosion ignited by the spark plug push the piston downwards.

Exhaust stroke

The turning motion of the crankshaft makes the piston moves upwards and opens up the exhaust valve to discharge the combustion gases out of the cylinder.

The above is a representation of the work process inside a car engine.

What is a car transmission and how does it work?

The transmission is an essential component for any car and is mounted directly onto the engine. Its primary function is to convert the mechanical energy produced by the engine into a momentum force that helps in driving the car wheels.

It is comprised of the clutch, the gearbox, propeller shaft, universal joints, rear axle, wheel, and tires. The vehicles which have a front-wheel drive, include a second set of propeller shafts, universal joints, final drives, and differentials for the front units.

The typical transmission system of a car has to meet the following requirements to successfully propel a car:

  • Provide means of connection and disconnection of the engine with the rest of the power trains without shock and also smoothly.
  • Provide varied leverage between the engine and the drive wheels.
  • Provide means to transfer power in the opposite direction.
  • Enable power transmission at varied angles and varied lengths.
  • Enable speed reduction between the engine and the drive wheels in a ratio of about 5:1.

What are the main types of transmission used in cars?

The 2 main types of transmission used in cars are:

  • Manual transmission
  • Automatic transmission

Manual transmission

A manual transmission comprises a manual gearbox that uses a stick to allow the driver to shift gears up or down. It usually comprises either 5 or 6 forward gears and 1 reverse gear.

The gears are shifted by making use of a clutch pedal that is located to the left of the car brake. Frequent and slow engagement of the clutch can result in premature wear out of the clutch disc.

 Although if the clutch is engaged rapidly, the engine suffers a potential stalling problem.

These are the following components that make up a manual gearbox:


The clutch is a device shaped like a disc and helps shift through the different gears inside the manual gearbox. It is the main source of transmitting the torque produced by the engine to the wheels.


The flywheel is mostly circular in shape and its main function is to transmit the torque produced by the engine to the drive wheels. It also helps in storing the energy produced by the engine and regulates the speed while idling or stopping the car.

Output and layshafts

The gears on the output shaft mesh or join the gears on the layshaft to turn the engine according to the seat gear.


These are circular teeth-shaped components that help in regulating the torque and speed provided to the drive wheels. Larger gears help in providing more torque and less speed, while smaller gears provide lesser torque and high speed.

Automatic transmission

The type of transmission in which various speeds are obtained automatically is known as an automatic transmission. The driver merely selects the car condition according to the different modes of the automatic transmission system.

Automatic transmissions need no gear change lever. They operate by controlling the vehicle speed and engine load. Increasing vehicle speed needs changing gears upwards, whereas increasing engine load helps change from higher to lower gears. The engine load-sensitive control unit is operated by the depression of the accelerator pedal.

These are the following components of an automatic transmission-driven car.

Torque converter

It helps in transferring the torque from the engine to the transmission input shaft. It also acts as a torque multiplier.

Transmission case

This casing acts as a housing for all the components involved in an automatic transmission.


The gears present in automatic transmissions are called planetary gears and they help to increase or decrease the gear ratios.

Research has shown a type of automatic transmission known as Continuously Variable Transmission(CVT) that uses a pulley system to change through gears without altering the gear ratios.


This blog post addressed the question, ‘What do you mean by a car engine and transmission?’

We understood the role of a car engine and how it works to produce mechanical energy. We also came across the transmission system that helps in transmitting this energy in the form of momentum to the drive wheels. Furthermore, the different types of transmission systems primarily found in cars have also been discussed. Please feel free to comment on the content or ask any questions in the comments section below.

Frequently Asked Questions(FAQs): What do you mean by a car engine and transmission?

What is the function of an engine?

A car engine receives an air-fuel mixture from the intake valve and burns it to produce power that is transferred to the wheels via a crankshaft to make it move.

Why do you need an engine in a car?

The engine of a car helps produce all the power necessary to run a vehicle and without it, a vehicle cannot function.

How many gears are in a car?

Mostly all cars are equipped with 5 or 6 sets of gears along with a set of gear chains.